PANDORA Project: Study of the photo-absorption response in light nuclei as input for UHECR propagation studies

Abstract

The PANDORA (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astro physics) project is dedicated to both experimental and theoretical analysis of photo-nuclear reactions involving light nuclei with a mass below A = 60. This research is particularly significant in the context of ultra-high-energy cosmic ray (UHECR) investigations, where the primary mode of energy attenuation is determined by the electromagnetic interaction of the nucleus with the cosmic microwave background through the isovector giant dipole resonance (IVGDR). Currently, propagation calculations and reaction models face challenges due to a lack of reliable experimental data sets for crucial nuclei. Results on 12C and 13C from an experiment conducted at the Research Center for Nuclear Physics (RCNP), Japan, using the virtual photon method on (p,p’) inelastic scattering reactions at 392 MeV experiment are presented. This was the first experiment when the Grand Raiden spectrometer was used in conjunction with the charged particle detection array SAKRA and the γ-ray detector array SCYLLA. Information such as the photoabsorption cross section associated with the IVGDR and the branching ratios for proton and α decay were extracted for 12C and 13C. This work is part of the first experiment of the PANDORA project. Besides supporting nuclear theory benchmarking, these results offer a first estimate of UHECR loss lengths, highlighting the impact of new data and the importance of inclusive datasets.